This excerpt taken from the UNH 8-K filed Oct 16, 2008.
USE OF NON-GAAP FINANCIAL MEASURES
Operating results excluding special items and adjusted cash flows from operations as used in the press release are not calculated in accordance with GAAP and should not be considered a substitute for or superior to financial measures calculated in accordance with GAAP. Management believes that the use of each of these non-GAAP financial measures improves the comparability of our results between periods. These financial measures provide investors and our management with useful information to measure and forecast our results of operations, to compare on a consistent basis our results of operations for the current period to that of prior periods, and to compare our results of operations on a more consistent basis against that of other companies in the health care industry.
These non-GAAP financial measures have limitations in that they do not reflect all of the special items or timing of certain cash payments/receipts associated with the operations of our business as determined in accordance with GAAP. As a result, one should not consider these measures in isolation. We compensate for these limitations by analyzing current and future results on a GAAP basis as well as non-GAAP basis, disclosing these GAAP financial measures, and providing a reconciliation from GAAP to non-GAAP financial measures.